Watch oil



Patented Dec. 19, 1950 FFiCE WATGH OIL Joseph S. Martin, .l in, Lancaster, Pa, assignor to Hamilton Watch Company, Lancaster, Pa,

No Drawing. Application February 12, 1949, Serial No. 76,179

7 Claims.

This invention relates to a lubricating oil particularly designed for bearings and that particular type of bearing used. in watches.

The lubrication of bearings of the type used in watches is becoming an increasingly difiicult problem as the size of the watch is constantly being reduced. The actual contact of the bear ing with the pivot is over an extremely small area. The application of the lubricant to the bearing is made at stated intervals which may be any-- where from a few months to years. It is necessary, therefore, that such a lubricant possess qualities which while desirable are not necessary in lubricating other types of bearings. The lubricating qualities should be such as to assure the efficient performance of the watch.

The oil should be only slightly volatile within ordinary range of temperatures; it must not spread to other parts of the watch but must remain in the position to which it is applied even though the position of the bearing constantly changes, that is with relation to the force of gravity; it should not oxidize or become gummy under ordinary temperatures which should run from below zero to 80 above 0 F.; it should not be corrosive; it should not solidify within the range of temperatures as suggested above; it

In order to establish a basis for comparison certain oils were subjected to a spread test as here outlined. Nine drops of oil spaced uniform- 1y on a square, three to a side with the center of the drops .125 inch apart, are placed on freshly greyed low carbon steel slugs and inserted in an oven at 140 F. At the end of two hour and four hour intervals they are observed and the condition of the droplets noted. Where the nine individual drops remain with the surface not wetted between the drops, the result and conclusion is Non-spread. Where nine drops remain with small wetted areas around one or more drops but with no wetted areas touching, the conclusion is termed Little Spread. Where nine drops remain with wetted areas merged between two or more drops, the conclusion is Spread. Where there are less than nine drops but more than one drop remaining, Much Spread. Where there is one drop remaining, the result is termed Very Much Spread and where there are no drops remaining, the tabulation Complete Spread is given. This renders six classifications which we will use hereinafter in the table below to compare the present oil of this invention with known types.

il'ould retain chemical stability throughout its Material spreadsRalfing e. 011 tee The cost of producing such an oil need not be taken into consideration as the quantity proe y ellosqlvephenylstearate Non-spread. duced is exceedingly small and as the application gg ggfigfggrg fifi gggigfiggg f to each individual watch is never more than two g ig g llittle spread. or three drops, he individual cost per Watch is 258 ec nd sci Minis 011 I c fiiiifjstmd. practically negligible. It is, therefore, seen that Silicone Oil while cost and economy does not enter the picture, the above described physical properties are essential and in addition the oil should be one whose properties can be maintained to close tolerances so that the behavior of the oil can be predicted and relied upon.

Fatty and mineral lubricants possess varying, spreading properties which leave considerable room for improvement. In order to eliminate the dependency on these oils as timepiece lubricants, this invention pertains to the development of an oil made from purified natural and synthetic organic chemicals and have proved their value in the final spread test. Many factors such as dusty atmosphere, perfumes, perspiration and evaporation contribute to the spread of watch oils and fatty oils are particularly susceptible to these. It has been found :by experiment that the true synthetic oil produces a favorable reaction when compared with the fatty oils.

The only functional method of comparison between the oil which is the subject matter of this invention and known oils is its relative performance during certain tests. These tests are, therefore, included in the description of the invention to set forth the comparative merit of this new oil over other oils. The following test is used to determine the coefiicient of friction of different watch lubricants and was devised in connection with the development of this oil.

This method of test is intended to provide a relative value of the oiliness or ability to lubricate, of various watch oils and greases. The control oil for this test shall be Drakeol seconds Saybolt viscosity white mineral oil for which the coeflicient of friction has been determined as- .096.

A pendulum type oiliness tester of the type used by Mr. G. E. Barker and described in the American Society for Testing Materials Bulletin for March 1946 is used with certain modifications as described below. In my test, the pendulum is pivoted on two ball bearings which roll on a sapphire surface, a type of pivot which can be quickly and readily cleaned and one which furnishes reliable comparative information. A thin film of oil is spread both on the sapphire surface and the ball bearings which have been previously cleaned and highly polished. The pendulum is allowed to swing and the amplitude observed and recorded to the nearest estimated tenth of a degree. The amplitude of each third successive period is likewise estimated and recorded until the twelfth period is reached. This procedure is repeated until five sets of reasonably consistent figures are obtained. The coefficient of friction is calculated as follows:

wherej=coefiicient of friction L=distance of the center of gravity from the point of suspension of the pendulum 0=ang1e between the vertical and the radius of the ball bearings at their point of tangency with the plane bearing sapphire surface r=average radius of the ball bearings Ao=amplitude of initial period in radians Au=amplitude of nth period in radians n=period of swing Duplicate tests are performed on the different oils and a control test run frequently on the 1. Setting-up test A small quantity of the standard dibutylphthalate is placed in the watch glass by means of a clean glass stirring rod. This watch glass and one of the test slides is placed on the block beneath the pin chuck of the hand press. The chuck is then lowered until the pins are about half submerged in the liquid. The pins are then withdrawn and the drops removed by touching the pins to the edge of the watch glass. The pins are again lowered into the dibutyl-phthalate and withdrawn. A few moments are allowed for drops to form on the ends of the pins. These drops are then transferred to the polished surface of the test slide by lowering the chuck until the drops just touch and adhere to the surface. The pins are then withdrawn by raising the chuck. Care should be taken to place the drops as nearly parallel and adjacent as possible to the polished edge. Measurements are taken on these drops as follows:

2. Measurement of drops The contact angle instrument is first leveled by placing a leveling bulb on the stage, and making the necessary adjustments to the four legs. The bulb is then replaced by the slide on which the 4 dibutyl-phthalate has been placed. One of the three drops is brought into the center of the microscope field by the horizontal and vertical position adjusters on the stage.

The diameter of the drop is measured with the fixed scale of the filar micrometer eyepiece in the horizontal position. The diameter is then found by moving the movable cross hair from one extremity of the drop to the other. The units traveled are noted on the Vernier drum and represent the diameter of the drop.

The height of the drop is measured by turning the eyepiece 90 so that the fixed scale is in a vertical position. The movable cross hair is made to coincide with the horizontal axis of the elliptical image. This cross hair is then moved until it just reaches the top of the drop. The units traveled represent the height of the drop.

This procedure is repeated on the other two drops. The measurements obtained are converted to contact angles according to the equation below:

Let h==height of drop measured by micrometer Let d=diameter of drop measured by micrometer then tan a= g a=2 tan Presuming that the drop being measured is a perfect arc of a circle then the contact angle is equal to 2 or twice the calculated angle.

The values for dibutyl-phthalate thus obtained should be as follows:

Degrees Steel slides 40 Ruby slides 40 The overall average between duplicate tests is taken as the contact angle of the oil under test.

Each test shall be performed in duplicate on both ruby and steel. The variation between the contact angles of the drops on any one slide may not exceed 3. If it is greater than 3 the test must be repeated. Also the averages of duplicate tests must agree within 3 or the test must be repeated.

Any deviation greater than 3 from these average values indicates that the slides are unfit for the testing of other oils and must be repolished and recleaned.

Experimental oils are tested in exactly the same manner as that just described for dibutylphthalate.

For the oxidation corrosion test which is performed upon this material as a qualifying condition for its use, metered moist air is bubbled for 96 hours through a 212 F. heated sample in which are immersed brass and steel slugs. Tests performed upon the oil exposed to these conditions measure gumming, development of acid and effect of the oil upon the metals so named. After the test, the oil shall not show more than 10 increase in viscosity nor exhibit an acid number greater than five (5). In addition, the brass and steel slugs shall not show a weight loss of more than 0.0005 gram.

The table below is included to show the relation of the physical and chemical properties of the new watch oil to other known watch oils.

Average laboratory test results upon various oils used as timepiece lubricants Material Laboratory Tests Phenyl n Raw Commercial gg??? Porpoise Jaw Oil N eats-foot Tricresyl Silicone Oil Stem, 'Oil Phosphate 1 Specific Gravity at 25 C... Refractive Index at 25 0.. Kinematic Viscosity at 25 F. Viscosity Index Steel Spread 70 Complete Spread... gum and stain 5 Non Spread; gum and rust. stain.

below 25.

below 25.

not performed..... not performed.

1 Test results vary according to purchase source of oil.

The preparation of phenyl stearic acid, the ester of which with phenyl Cellosolve or ethylene glycol monophenyl ether, is the main ingredient of the oil forming the subject matter of the invention. A special processed F. cold test neats-foot oil is used as the base in the preparation of phenyl stearic acid. This oil, which consists of the mono-, diand tri-glycerides of palmitic, oleic and stearic acids, is converted to the respective methyl esters and vacuum distilled to isolate methyl oleate. The methyl oleate is then condensed with benzene by anhydrous aluminum chloride, thereby saturating the organic acid to phenyl methyl stearate. The CcHs or phenyl group is added to the methyl oleate at either the #9 or #10 carbon atoms. The phenyl stearic acid, which is obtained by saponification and acidulation, is thereby an inseparable mixture of 9- and 10-phenyl stearic acids, and requires only the determination of neutral equivalent and refractive index to confirm its identity before using it in additional syntheses.

The preparation of phenyl stearic acid from the neats-foot oil is carried out in five stages, the first of which is the alcoholysis of the neatsfoot oil with methyl alcohol in which the neatsfoot oil is combined with the alcohol to produce a methyl neats-foot ester.

The second step is the processing of the ester to form a methyl oleate by fractionally distilling the ester under reduced pressure to produce the oleate which should have the following constants: ND 1.4485-L4500, acid neutral equivalent 280-282 and a kinematic viscosity of 4.5 to 5.0 centistokes at 100 F.

The third step is the condensation of the methyl oelate with benzene by anhydrous aluminum chloride.

The fourth stage in the preparation is the puriflcation of the phenyl methyl stearate. This is accomplished by repeated washings and filterings, paying particular attention to eliminating acid reactions.

The fifth and final step is the preparation of the phenyl stearic acid by adding to the phenyl methyl stearate, an excess of potassium hydroxide for complete saponification and a quantity of methyl alcohol equal to the quantity of phenyl methyl stearate. The methyl alcohol-soap mixture is evaporated and the soap dissolved with distilled water. Dilute acetic acid is used toliberate the phenyl stearic acid which isthen washed with distilled water until the washings are neutral. This phenyl stearic acid is the principal ingredient of the oil forming the subject of this invention. The following equations trace this preparation from the methyl oleate: In order to provide a graphic account of the synthesis of phenyl stearic acids, the equations below trace its preparation from methyl oleate. For convenience, the phenyl group is pictured on the #10 carbon atom, although as mentioned before, a mixture of 9- and lO-phenyl stearic acids is actually the case.

1. OH3(CHz)1CH=OH(CE2)COO0H3 AlCh cni cnoicncicnnucn) onaiooocni H2O CH3(CH2)7CH(C5H )CH(A1C12)(CH2}7COOCHs cnuonmonwim)cngonmoooon AICIQOH The ester of the phenyl stearic acid with phenyl Cellosolve (ethylene glycol monophenyl ether) is the principal ingredient of the oil which is the subject matter of this invention. The foregoing has described the preparation of the phenyl stearic acid which will now be combined with phenyl Cellosolve and an ester of the two formed according to the following procedure.

To a predetermined weight of phenyl stearic acid, an excess of phenyl Cellosolve is added followed by one percent by weight of para toluene sulfonic acid. This mixture is refluxed for more than twelve hours and the water of reaction removed by azeotropic distillation with an excess of toluene.

The crude ester is dissolved in a suitable solvent, made alkaline with a 10% aqueous sodium carbonate solution and washed with distilled water until neutral and dried. The solvent is then removed and the ester vacuum distilled at 300 C. at 1 mm. pressure. The ester thus obtained is tested to meet requirements of viscosity and refractive index. These tests are extremely critical and the results are held to extremely close tolerances. To the ester which successfully meets these requirements, 1% by weight of an oiliness agent of the oxygenated-hydrocarbon type consisting predominately of alcohols, ketones, and methyl esters is added thoroughly dissolved and the resultant mixture is filtered. The oil in this agent used is Alox 350. Alox 350 is derived from the controlled oxidation of fractions of Pennsylvania petroleum. It belongs to a group consisting fundamentally of mixtures of organic acids and their esters ranging from C5 to C35, but they also contain high-molecular weight alcohols, lactones, ketones, and alcohol-ketones. The properties of Alox 350 may be outlined as specific gravity at 158 F. .8927 to .8861, viscosity, Saybolt sec. at 210 F. 68-80, melting point 100 to 110 F., flash point 300 to 340 F., acid No. 15-20, saponification No. 90-115. This resultant mixture is the oil which forms the subject of the invention.

What is claimed is:

1. A lubricant consisting of the ester of phenyl Cellosolve (mono-phenyl ether of ethylene glycol) and 9- and 10-phenyl stearic acid.

2. A lubricant consisting of the ester of phenyl Cellosolve (mono-phenyl ether of ethylene glycol) and 9- and 10-phenyl stearic acid containing from .05% to 5% by weight of Alox 350.

3. A lubricant consisting of an ester of phenyl Cellosolve (mono-phenyl ether of ethylene glycol) and 9- and IO-p-henyl stearic acid, said acid formed from an oleate of methyl ester of the glycerides of neats-foot oil, reacting said oleate with benzene in the presence of anhydrous aluminum chloride, from said action isolating phenyl methyl stearate and forming the said phenyl stearic acid from the result.

4. A lubricant formed of an ester of phenyl "Cellosolve (mono-phenyl ether of ethylene glycol) and 9- and 10-phenyl stearic acid physically characterized when in drop form of a contact angle of greater than 40.

5. A lubricant formed of an ester of phenyl "Cellosolve (mono-phenyl ether of ethylene glycol) and 9- and 10-phenyl stearic acid physically characterized by being non-corrosive and having a contact angle when in drop form of greater than 40.

6. A lubricant formed of an ester of phenyl Cellosolve (mono-phenyl ether of ethylene glycol) and 9- and l0-phenyl stearic acid physically characterized by its non-spreading qualities, said oil remaining in drop form on steel with a contact angle of greater than 40, of being noncorrosive, of having a coefificient of friction of 0.0800 between steel and sapphire and of having a specific gravity at C. of .97.

'7. A lubricant formed of an ester of phenyl Cellosolve (mono-phenyl ether of ethylene glycol) and 9- and IO-phenyl stearic acid physically characterized by being non-corrosive, having a contact angle when in drop form of greater than 40, having a viscosity index of and a coefficient of friction of .080 between steel and sapphire.

JOSEPH S. MARTIN, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,173,117 Johnson Sept. 19, 1939 2,211,163 Reis Aug. 13, 19 0 2,345,006 Ross Mar. 28, 1944 2,355,615 Barker Aug. 15, 1944 2,409,44 Morgan Oct. 15, 1946 OTHER REFERENCES Handbook of Material NamesZimmerman and Lavine, Industrial Research Service, 1946, page 24 pertinent. 

1. A LUBRICANT CONSISTING OF THE ESTER OF PHENYL "CELLOSOLVE" (MONO-PHENYL ETHER OF ETHYLENE GLYCOL) AND 9- AND 10-PHENYL STEARIC ACID. 